CVE-2025-0376: GitLab CE/EE XSS Vulnerability

CVE-2025-0376 Overview

A Cross-Site Scripting (XSS) vulnerability exists in GitLab Community Edition (CE) and Enterprise Edition (EE) affecting all versions from 13.3 prior to 17.6.5, 17.7 prior to 17.7.4, and 17.8 prior to 17.8.2. This vulnerability allows an attacker to execute unauthorized actions via a change page, potentially compromising user sessions and enabling malicious script execution in the context of authenticated users.

Critical Impact
This XSS vulnerability enables attackers to execute arbitrary JavaScript in victims' browsers, potentially leading to session hijacking, credential theft, and unauthorized actions on behalf of authenticated GitLab users.

Affected Products

GitLab Community Edition (CE) versions 13.3 to 17.6.4
GitLab Enterprise Edition (EE) versions 13.3 to 17.6.4
GitLab CE/EE versions 17.7.0 to 17.7.3
GitLab CE/EE versions 17.8.0 to 17.8.1

Discovery Timeline

2025-02-12 - CVE-2025-0376 published to NVD
2025-08-06 - Last updated in NVD database

Technical Details for CVE-2025-0376

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw exists within GitLab's change page functionality, where user-supplied input is not properly sanitized before being rendered in the browser. This allows attackers to inject malicious scripts that execute in the security context of other users viewing the affected page.

The vulnerability requires user interaction to exploit, as victims must navigate to a specially crafted page or click a malicious link. When successfully exploited, the attacker's JavaScript code executes with the same privileges as the victim, enabling actions such as stealing session cookies, performing actions on behalf of the user, or redirecting users to malicious sites.

Root Cause

The root cause of this vulnerability stems from insufficient input validation and output encoding within GitLab's change page functionality. When processing user-controlled data, the application fails to properly sanitize or escape special characters that have meaning in HTML/JavaScript contexts. This allows attackers to break out of the expected data context and inject executable script content.

Attack Vector

The attack leverages the network-accessible GitLab web interface and requires user interaction. An attacker can craft a malicious URL or page element that, when accessed by a victim, causes their browser to execute attacker-controlled JavaScript. The scope is changed, meaning the vulnerability can affect resources beyond the vulnerable component's security scope, potentially impacting other applications or domains that trust the GitLab instance.

The exploitation scenario involves an attacker creating or manipulating content on a change page to include malicious script payloads. When another user (particularly administrators or users with elevated privileges) views this content, the script executes, potentially allowing the attacker to:

Steal session tokens and authentication cookies
Perform unauthorized actions as the victim user
Access sensitive repository data or project configurations
Modify code or settings within the user's accessible projects

Detection Methods for CVE-2025-0376

Indicators of Compromise

Unusual JavaScript execution patterns in GitLab web application logs
Unexpected outbound connections from client browsers to unknown domains when accessing GitLab
Reports from users of unexpected redirects or pop-ups when viewing change pages
Authentication tokens or cookies being accessed by unauthorized scripts

Detection Strategies

Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
Monitor web application firewall (WAF) logs for XSS payload patterns targeting GitLab endpoints
Review GitLab application logs for suspicious requests containing encoded script content
Deploy browser-based XSS detection extensions in test environments to identify vulnerable pages

Monitoring Recommendations

Enable verbose logging for GitLab web requests and monitor for unusual input patterns
Configure alerting for CSP violation reports if implemented
Monitor for anomalous user session behavior that may indicate session hijacking
Review access patterns to change pages for signs of targeted exploitation attempts

How to Mitigate CVE-2025-0376

Immediate Actions Required

Upgrade GitLab CE/EE to version 17.6.5, 17.7.4, or 17.8.2 or later immediately
Review recent activity on change pages for signs of malicious content injection
Invalidate active user sessions if compromise is suspected
Implement or strengthen Content Security Policy headers as a defense-in-depth measure

Patch Information

GitLab has released security updates that address this vulnerability. Organizations should upgrade to one of the following patched versions based on their current deployment:

For versions in the 17.6.x branch: Upgrade to 17.6.5 or later
For versions in the 17.7.x branch: Upgrade to 17.7.4 or later
For versions in the 17.8.x branch: Upgrade to 17.8.2 or later

Additional technical details and discussion can be found in the GitLab Issue Discussion and the original HackerOne Report #2930243.

Workarounds

Implement strict Content Security Policy (CSP) headers to mitigate XSS impact if immediate patching is not possible
Restrict access to GitLab instances to trusted networks while awaiting patch deployment
Educate users about the risks of clicking untrusted links that direct to GitLab pages
Consider temporarily disabling or restricting access to change page functionality if feasible

bash

# Example CSP header configuration for nginx (defense-in-depth)
# Add to GitLab nginx configuration
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; connect-src 'self';" always;